Smarter people go to bed later

Got numbers to show it. And it may be true. The question is whether going to bed later makes you smarter, or whether smarter people choose to go to bed later, need less sleep, think too much and can't get to sleep, have more to do, or what.

From Psychology Today:

Night Lights

Bedtimes and wake-up times for Americans in their 20s by IQ.

Very Dull (IQ < 75)

Weekday: 11:41 P.M.-7:20 A.M.

Weekend: 12:35 A.M.-10:09 A.M.

Normal (90 < IQ < 110)

Weekday: 12:10 A.M.-7:32 A.M.

Weekend: 1:13 A.M.-10:14 A.M.

Very Bright (IQ > 125)

Weekday: 12:29 A.M.-7:52 A.M.

Weekend: 1:44 A.M.-11:07 A.M.